1. Field of the Invention
The present invention relates to a reducer and an electric power steering apparatus having the same, and more particularly to a reducer which improves a conventional configuration, in which a motor inevitably protrudes since a motor shaft, an input shaft, a driving shaft, a pinion shaft, etc. are coaxially arranged, to be capable of preventing the motor from interfering with other structures such that a layout configuration in an apparatus can be compactly formed, and an electric power steering apparatus having the reducer.
2. Description of the Prior Art
FIG. 1 is a view illustrating a configuration of a conventional electric power steering apparatus for a vehicle.
As illustrated in FIG. 1, a conventional electric power steering apparatus 100 for a vehicle includes a steering system leading from a steering wheel 101 to opposite vehicle wheels 108 and an auxiliary power mechanism 120 configured to supply a steering assistance force to the steering system.
The steering system includes a steering shaft 102 of which one end is connected to the steering wheel 101 and the other end is connected to a driving shaft via a universal joint 103.
The driving shaft includes an input shaft 104 connected with the steering shaft 102 and a pinion shaft 106 connected with the input shaft 104 via a torsion bar (not illustrated) and formed with a pinion gear 111 at a lower end thereof.
The pinion gear 111 formed on the pinion shaft 106 is teeth-engaged with a rack gear 112 formed at one end of the outer circumferential surface of a rack bar 109, and the opposite ends of the rack bar 109 are connected to the vehicle wheels 108 through tie rods 151 and knuckle arms 153.
The auxiliary power mechanism 120 includes a torque sensor 125 configured to sense a torque generated in the input shaft 104 when a driver operates the steering wheel 101 and output an electric signal which is proportional to the sensed torque, an Electronic Control Unit (ECU) 123 configured to generate a control signal based on the electric signal transmitted from the torque sensor 125, a motor 130 configured to generate an auxiliary power based on the control signal transmitted from the electronic control unit 123, and a worm 141 and worm wheel 143 configured to transmit the auxiliary power generated by the motor 130 to the pinion shaft 106.
In the conventional electric power steering apparatus for a vehicle, the motor, the worm, the worm wheel, etc. are used as components for the reducer of the auxiliary power mechanism. Thus, when the components are equipped in a vehicle, the motor inevitably protrudes to interfere with other structures, which is disadvantageous in terms of the layout.